Electronic thread guard

ABSTRACT

An electronic thread guard for guarding a plurality of threads or groups of threads comprising a first set of glow discharge lamps, there being one lamp for each thread or thread group to be guarded, and a series resistor connected with the set between two supply voltage leads. A second set of lamps, there being one lamp with a voltage dropping resistor for each thread or thread group to be guarded, is connected between the two supply voltage leads. A light-dependent resistor included for each thread or thread group is illuminated or obscured in response to tensioning or slackening, respectively, of the corresponding thread or thread group and is connected to a corresponding one of the lamps in the first set and to a corresponding lamp in the second set. In response to the occurrence of a break in one of the threads or thread groups, the corresponding glow discharge lamp in the first set is ignited, and ignition of the other lamps in that set is prevented. The voltage across or current through the series resistor is utilized to stop the machine, and each lamp in the second set is ignited independently in response to slackening of the corresponding thread or thread group.

United States Patent [72] lnventor Geert Jan Vermeulen Deurne,Netherlands [21] Appl. No. 755,346

[22] Filed Aug. 26, 1968 [45] Patented Apr. 27, 1971 [73] Assignee N. V.Maehinefabriek L. te Strake Deurne, Netherlands [3 2] Priority Sept. 12,1967 [3 3] Netherlands [54] ELECTRONIC THREAD GUARD 6 Claims, 1 DrawingFig.

[52] US. Cl 340/259, 57/81, 139/336, 250/206, 250/215, 315/134,

[51] Int. Cl G08b 19/00 [50] Field ofSearch 340/222, 220, 259, 419, 421,146.1; 250/206, 215; 57/81,

109; 139/336; 200/6l.l3,6l.l8; 315/149, 155,

3,298,401 l/1967 Stutz 139/371 3,345,812 10/1967 Pickering 340/259X3,365,647 1/1968 Stone 250/206X 3,440,634 4/1969 Maurmann et al 340/259Primary ExaminerJohn W. Caldwell Assistant Examiner-David L. TraftonAtt0rney-Christel & Bean for each thread or thread group to be guarded,is connected between the two supply voltage leads. A light-dependentresistor included for each thread or thread group is illuminated orobscured in response to tensioning or slackening, respectively, of thecorresponding thread or thread group and is connected to a correspondingone of the lamps in the first set and to a corresponding lamp in thesecond set. In response to the occurrence of a break in one of thethreads or thread groups, the corresponding glow discharge lamp in thefirst set is ignited, and ignition of the other lamps in that set isprevented. The voltage across or current through the series resistor isutilized to stop the machine, and each lamp in the second set is ignitedindependently in response to slackening of the corresponding thread orthread group.

ELECTRONIC THREAD GUARD lnmany textile machines, such as twiningmachines, creels and warping machines, thread guards are used forsignaling the breakage of a thread or thread group and for stopping themachine. Upon the machine coming to a stop, usually many threads orthread groups which have not broken become slack, so that it is notsimple to ascertain in which thread or thread group a break must berepaired before the machine can be restarted. Therefore, there is a needfor a thread guard which indicates and continues to indicate, even afterthe machine has come to a stop, in which thread or thread group a breakhas occurred and which moreover possibly continues to indicate whichthread or thread groups are slack, regardless of whether this has beencaused by a thread breakage or not. The latter point is of importancefor indicating to the operators after repairing the thread breakage,which threads or thread groups are still to be tensioned before themachine can be restarted.

The invention aims at providing an electronic thread guard which meetsthe above requirements.

For that purpose it is a feature of an electronic thread guard accordingto the invention that for each thread or thread group to be guarded, aglow discharge lamp and a seriesresistor in the order mentioned areconnected in series between two supply leads which with respect to oneanother carry a stabilized voltage somewhat exceeding the ignitionvoltage of the glow discharge lamp, the series resistor being common toall resistors and glow discharge lamps and in which between the junctionof each first resistor and first glow discharge lamp and a supply pointwith a lower voltage than that junction respectively, a light-dependentresistor is connected, which by intervention of a vane operated by thethread or thread group concerned, is illuminated as long as the threador thread group concerned is tensioned and becomes obscured as soon asthe thread or thread group concerned becomes slack.

As will be explained below, the glow discharge lamp concerned ignites assoon as a break occurs in a thread or thread group and the lamp remainsignited also after the machine has been stopped. In that case, noindication is obtained of the thread or thread groups which by stoppingthe machine have also become slackened. If that is required, it can be afurther feature of the device according to the invention, that thesupply point with a lower voltage than the junction, for eachlight-dependent resistor consists of a separate second glow dischargelamp which with one terminal is connected to the supply lead to whichthe resistors are connected and with the other terminal through a secondresistor is connected to the other supply lead.

In that case, as soon as further threads or thread groups becomeslackened by the machine stopping, the corresponding second glowdischarge lamps ignite also, but the corresponding first glow dischargelamps remain extinguished, so that eventually the ignited first glowdischarge lamp indicates in which thread or thread group a break hasoccurred while the ignited second glow discharge lamps indicate whichthreads or threadgroups have finally become slackened, regardless ofwhether this has been caused by a thread breakage or otherwise.

The invention is further elucidated below with reference to the DRAWING,which shows a circuit diagram of an embodiment of a thread guardaccording to the invention.

In the FlGURE, a stabilized voltage of e.g. 90 volts exists between thesupply leads 1 and 2. A series resistor 3 is connected to the supplylead 2 and between its free terminal and the supply lead 1, glowdischarge lamps 4, 5 with eacha resistor 6, 7 in series are connected.For each thread or thread group to be guarded, a separate glow dischargelamp in series with a resistor is present. Further, glow discharge lamps8, 9, each in series with a resistor 10, 11 are connected between thesupply leads 1 and 2 and of these glow discharge lamps also, a separateone is present for each thread or thread group to be guarded. Thejunction of each of the first glow discharge lamps and resistors isthrough a separate light-dependent re- .sistor 12, 13 connected to thejunction of the corresponding second glow discharge lamp and resistor.All glow discharge lamps 4, 5, 8, 9 have ignition voltages which aresomewhat below the supply voltage, e.g. ignition voltages .of 75 volts.

As long as all threads or thread groupsto be guarded are tensioned, i.e.during normal operation of the machines, the respective vanes assumesuch positions that the light-dependent resistors 12, 13 are illuminatedby the ambient light or a lamp specially provided for that purpose.Theseresistors thereby have a low resistance, e.g. of the order of 10k0. The resistors 6, 7 and 10, 11 have resistances of the same order ofmagnitude, e.g. also 10 k0. The voltage drop across each of theconventional resistors 6, 7 and 10, 11 thereby amounts to approximately30 volts and the voltage drop across each of the light-dependentresistors 12, 13 also amounts to approximately 30 volts. The voltagewhich is available for the glow discharge lamps 4, 5, 8, 9 for thatreason is not higher than approximately 60 volts, which is far below theignition voltage,

so that these lamps cannot ignite. As soon as one of the threads orthread groups to be guarded breaks, e.g. the thread or thread groupwhich operates the vane which determines the illumination of thelight-dependent resistor 12, this light-dependent resistor becomesobscured, whereupon its resistance rises strongly and e.g. reaches avalue of the order of magnitude of 1 MO. The voltage drop across therespective resistors 6 and 11 respectively in that case becomes verysmall, so that substantially the full supply voltage becomes availablefor the glow discharge lamp 4 and 9 respectively, which are ignitedthereby. Ignition of the glow discharge lamp 4 indicates that the threador thread group belonging to this lamp has broken. At the same time, themachine is automatically stopped by a device which responds to thevoltage across or the current through the common series resistor 3. Thisdevice can e.g. consist of a relay, the coil of which takes the place ofthe series resistor 3, or of a relay, the coil of which is connected tothe series resistor 3, possibly through an amplifier. Upon the machinestopping, the nonbroken threads or thread groups 2 will generally becomeslackened, in this case e. g. the thread or thread group whichcooperates with the vane of the light-dependent resistor 13. Thereby,this light-dependent resistor too assumes a very high resistance, sothat the voltage drop across the resistors 7 and 10 respectively becomesvery small. Thereupon, substantially the full supply voltage isavailable for the glow discharge lamp 8, so that this glow dischargelamp also ignites, indicating that the thread or thread group concernedhas become slackened. The glow discharge lamp 5 on the other hand is notable to ignite, since the voltage drop across the series resistor 3,caused by the current through the glow discharge lamp 4 which hasalready been ignited, is so large that the voltage available for theglow discharge lamp 5 is below the ignition voltage of that lamp.Therefore, among the first glow discharge lamps 4, 5 only that lamp canignite, which correspond to the thread or thread group in which a breakhas occurred.

Upon putting the machine back in operation, first of all the break isrepaired in the thread or the thread group to which the glow dischargelamp 4 belongs. Subsequently, this thread or thread group is tensionedand thereupon, all other threads or thread groups, the glow dischargelamps 8 or 9 of which have been ignited, are tensioned too. By a shortinterruption of the supply voltage,-all ignited glow discharge lamps areextinguished and upon switching the supply voltage on again,

these do not ignite again, since all light-dependent resistors- .fore,in practice a correspondingly larger number of glow discharge lamps,resistors and light-dependent resistors is used. In certain cases, thelight-dependent resistor can be replaced by microswitches, but thesehave the disadvantage of a much lower mechanical sensitivity than avane.

If it is not necessary to indicate which thread or thread groups havebecome slackened upon the machine stopping, even if no break hasoccurred in these threads or thread groups, the right hand terminals ofthe light-dependent resistors l2 and 13 can be connected directly to thesupply lead 2 or the tap of a voltage divider between the supply leads 1and 2. The second glow discharge lamps 8 and 9 and the resistors 10 and11 are then superfluous. v

I claim: 1. An electronic thread guard comprising a plurality ofresistors each connected to a first supply lead, a corresponding 7plurality of glow discharge lamps connected to corresponding ones ofsaid resistors, there being one series combination of resistor and glowdischarge lamp for each thread or thread group to be guarded, a seriesresistor connected to said glow discharge lamps and a second supplylead, whereby each resistor, each glow discharge lamp and said seriesresistor in the above order are connected in series between the twosupply leads which with respect to one another carry a stabilizedvoltage which somewhat exceeds the ignition voltage of the glowdischarge lamps, the series resistor being common to all resistors andglow discharge lamps, a light-dependent resistor connected between thejunction of each resistor and glow Y discharge lamp and a supply pointwith a lower voltage than that junction respectively, saidlight-dependent resistor being illuminated as long as the thread orthread group concerned is tensioned and becoming obscured as soon as thethread or thread group concerned becomes slackened whereby in responseto the occurrence of a break in one of the threads or thread groups thecorresponding glow discharge lamp is ignited and ignition of the otherlamps is prevented.

2. Electronic thread guard, according to claim 1, wherein the supplypoint with a lower voltage than the junction for each light-dependentresistor comprises a separate second glow discharge lamp of which oneterminal is connected to said first supply lead to which the resistorsare connected and the other terminal is connected through a secondresistor to said second supply lead.

3. Electronic thread guard according to claim 1 wherein the circuitincludes a device which stops the machine as soon as the voltage acrossor the current through thefseries resistor exceeds a predetermined valueby the ignition of one of the first glow discharge lamps 4. Electronicthread guard according to claim 2 wherein the circuit includes a devicewhich stops the machine as soon as the voltage across or the currentthrough the series resistor exceeds a predetermined value by theignition of one of the first glow discharge lamps.

5. An electronic thread guard for guarding a plurality of threads orgroups of threads comprising a first set of glow discharge lamps, therebeing one lamp having a voltagedropping means connected thereto for eachthread group to be guarded, a series resistor, said first set of lampsand said series resistor being connected in series between first andsecond voltage supply leads which carry therebetween a stabilizedvoltage somewhat greater than the ignition voltage of each of said glowdischarge lamps, a second set of glow discharge lamps, there being onelamp having a voltagedropping means connected thereto for each thread orthread group to be guarded, a plurality of light-dependent resistors,there being one resistor for each thread or thread group to be guarded,each light-dependent resistor being illuminated as long as thecorresponding thread or thread group is tensioned and becoming obscuredas soon as the thread or thread group becomes slackened, each of saidlight-dependent resistors being connected to a corresponding one of saidlamps and voltagedropping means in said first set and to one of saidlamps and voltage-dropping means in said second set whereby in responseto the occurrence of a break in one of the thread or thread groups, thecorresponding glow discharge lamp in the first set is ignited andignition of the other lamps in that set is prevented and each lamp insaid second set is ignited independently in response to slackening ofthe corresponding thread or thread group.

6. An electronic thread guard according to claim 5 wherein the circuitincludes a device which stops the machine as soon as the voltage acrossor the current through said series resistor exceeds a predeterminedvalue by the ignition of one of said glow discharge lamps in said firstset.

1. An electronic thread guard comprising a plurality of resistors eachconnected to a first supply lead, a corresponding plurality of glowdischarge lamps connected to corresponding ones of said resistors, therebeing one series combination of resistor and glow discharge lamp foreach thread or thread group to be guarded, a series resistor connectedto said glow discharge lamps and a second supply lead, whereby eachresistor, each glow discharge lamp and said series resistor in the aboveorder are connected in series between the two supply leads which withrespect to one another carry a stabilized voltage which somewhat exceedsthe ignition voltage of the glow discharge lamps, the series resistorbeing common to all resistors and glow discharge lamps, alight-dependent resistor connected between the junction of each resistorand glow discharge lamp and a Supply point with a lower voltage thanthat junction respectively, said lightdependent resistor beingilluminated as long as the thread or thread group concerned is tensionedand becoming obscured as soon as the thread or thread group concernedbecomes slackened whereby in response to the occurrence of a break inone of the threads or thread groups the corresponding glow dischargelamp is ignited and ignition of the other lamps is prevented. 2.Electronic thread guard, according to claim 1, wherein the supply pointwith a lower voltage than the junction for each light-dependent resistorcomprises a separate second glow discharge lamp of which one terminal isconnected to said first supply lead to which the resistors are connectedand the other terminal is connected through a second resistor to saidsecond supply lead.
 3. Electronic thread guard according to claim 1wherein the circuit includes a device which stops the machine as soon asthe voltage across or the current through the series resistor exceeds apredetermined value by the ignition of one of the first glow dischargelamps.
 4. Electronic thread guard according to claim 2 wherein thecircuit includes a device which stops the machine as soon as the voltageacross or the current through the series resistor exceeds apredetermined value by the ignition of one of the first glow dischargelamps.
 5. An electronic thread guard for guarding a plurality of threadsor groups of threads comprising a first set of glow discharge lamps,there being one lamp having a voltage-dropping means connected theretofor each thread group to be guarded, a series resistor, said first setof lamps and said series resistor being connected in series betweenfirst and second voltage supply leads which carry therebetween astabilized voltage somewhat greater than the ignition voltage of each ofsaid glow discharge lamps, a second set of glow discharge lamps, therebeing one lamp having a voltage-dropping means connected thereto foreach thread or thread group to be guarded, a plurality oflight-dependent resistors, there being one resistor for each thread orthread group to be guarded, each light-dependent resistor beingilluminated as long as the corresponding thread or thread group istensioned and becoming obscured as soon as the thread or thread groupbecomes slackened, each of said light-dependent resistors beingconnected to a corresponding one of said lamps and voltage-droppingmeans in said first set and to one of said lamps and voltage-droppingmeans in said second set whereby in response to the occurrence of abreak in one of the thread or thread groups, the corresponding glowdischarge lamp in the first set is ignited and ignition of the otherlamps in that set is prevented and each lamp in said second set isignited independently in response to slackening of the correspondingthread or thread group.
 6. An electronic thread guard according to claim5 wherein the circuit includes a device which stops the machine as soonas the voltage across or the current through said series resistorexceeds a predetermined value by the ignition of one of said glowdischarge lamps in said first set.